There's a web interface for those dealing with the hardware infrastructure that underpins of your private cloud, but not for the admin charged with using it. You access those Eucalyptus APIs through the command line.

There are, however, third-party platforms that can front Eucalyptus with a GUI admin console - a browser-based tool for designing, implementing, and monitoring your virtual infrastructure. RightScale - founded by Thorsten von Eicken, a former academic research colleague of Amazon chief technology officer Werner Vogels - is the most prominent example. And if you're dead set on open-source, there's Scalr - a tool developed and commercialized by a startup based in the heart of Silicon Valley.

Scalr began as a management console for Amazon Web Services, and since the Eucalyptus APIs are compatible with Amazon's, it hooks into Ubuntu's Koala food as well. The same goes for RightScale - though von Eicken's platform can front other cloud services as well, including GoGrid and Rackspace's Cloud Servers.

In addition to offering a GUI where you can spin up server instances from either EC2 or Eucalyptus, Scalr is meant to facilitate a virtual infrastructure that's more redundant and, yes, scalable. It does elastic load balancing, automatically distributing incoming traffic across multiple server instances - something that Amazon offers but not Eucalyptus.

According to Scalr chief executive Sebastian Stadil, the tool is also designed to auto-configure and scale your database for backups and replication. And soon, he says, it will be able to push traffic onto EC2 if you exceed capacity on Eucalyptus.

Stadil - founder of the Silicon Valley Cloud Computing Group - goes on to say that Scalr provides applications on Eucalyptus with an added level of redundancy, claiming its responds better when instances go down. If a service that Scalr monitors is unresponsive, it it cuts all traffic to the instance and replaces it.

The platform also handles auto scaling, adding more servers to a cluster and distributing load among them, according to RAM or CPU usage, bandwidth, and more. It provides graphical tools for monitoring server usage. And its load balancer can provider users with "sticky" servers, giving the same person the same server every time they log in.

Scalr is available in as web service at Scalr.net or you can install the platform on your own servers. Both options use the same open source code.

The service - intended for small and medium-sized businesses - is free for websites in development, then it's $99 a month for an unlimited number of instances. For the local enterprise version, Red Hat-like support contracts are available.

Like Amazon Web Services, Eucalyptus provides on-demand access to scalable compute and storage resources. But whereas EC2, S3, and EBS run in Amazon's distant data centers, serving the world at large, Eucalyptus is meant for internal use. It runs in your data center and provides resources to employees or constituents.

NASA's Ames research center is using Eucalyptus to build its Nebula infrastructure cloud, which will apparently be used to house applications for various federal agencies.

The latest release of Ubuntu comes bundled with Eucalyptus. And that's why it's known - in Shuttleworthian fashion - as Karmic Koala. ®